The effect of working pressure, processing time, and salt addition on formation of free radicals in chicken breast and thigh muscle was investigated by electron spin resonance (ESR) spectroscopy using alpha-(pyridyl-1-oxide)-N-tert-butylnitrone (POBN) as spin trap in order to detect early events in lipid oxidation following high-pressure meat processing. Chicken breast and thigh with and without 3.0% salt added were subjected to high hydrostatic pressure at 200, 400, 600, 800, and 1000 MPa for 5, 15 (only breast), and 30 min. Radical formation increased with increasing pressure and processing time and reached a maximum value in chicken breast for 15 min of processing at 1000 MPa and in chicken thigh for 5 min of processing at 600 MPa. Radical formation was found to be more significant in thigh meat compared to breast meat and salt addition further promoted radical formation in chicken breast and especially in chicken thigh.2235669673